1. Field of the Invention
The present invention relates to a plunge base router and, in particular, to a plunge base having a number of advantageous features for facilitating use of the router in either an upright position or an inverted position. The inventive features of the plunge router of the present invention include a depth adjustment mechanism, a depth stop mechanism, a post-lock mechanism, and a return spring defeat mechanism.
2. Scope of the Prior Art
Plunge base routers have long been used to make grooves and cuts of various types. Such routers include a housing having a motor which rotates a router bit for making grooves and cuts in a work. The housing is vertically movable relative a base on two guide posts that are connected to the base. It is known that a plunge base router can be used in an upright (or normal position) and an inverted position for use under a router table. In the upright position, the router can plunge on the posts and is used to make cutouts, for grooving and edge-forming of wood or other solid-surface materials. When the router is mounted under the table, it is used like a shaper mainly for cutting repetitive shapes and for heavy decorative edge-cuts. When used in the upright position, the term cutting depth is used to describe the amount that the bit is exposed through the base. When used in the inverted position, the term cutting height describes the amount that the bit is exposed above the router table.
Typically, the housing of the plunge base router is slidable on the guide posts to permit plunging of the router and positioning of the housing relative to the base. The housing contains a compression spring adjacent to at least one of the guide posts for biasing the housing away from the base. The compression spring may be on the outside or inside of the post.
Most plunge base routers provide a depth adjustment mechanism to accurately position the bit at the correct cutting depth or height. Some routers provide a course adjustment mechanism to generally find the depth or height and a fine adjustment mechanism to accurately locate the depth or height. The course and fine adjustment mechanisms are both used to arrange the router for the desired cutting depth or height.
The prior art plunge base routers typically include a fine adjustment mechanism that is separate from the course adjustment mechanism. In such mechanisms, the fine adjustment mechanism typically has a short range of travel for fine tuning the adjustment of the course adjustment mechanism. Thus, if it is determined after making a cut that a larger adjustment is needed, both the course adjustment mechanism and the fine adjustment mechanism must be reset. The process of resetting both the course and fine adjustment mechanisms is fairly time consuming because both adjustment mechanisms must be zeroed again and the cutting depth or height completely reset. It is therefore believed to be desirable to have a plunge base router where the course and fine adjustment mechanisms are interdependent so that they do not have to be reset and zeroed repetitively.
A number of prior art plunge base routers are shown in issued U.S. Patents. For example, U.S. Pat. No. 4,770,573 to Monobe et al. discloses a plunge base router that uses a bolt and nut mechanism for course adjustment. The nut mechanism moves between a released position so that the plunge base router can be adjusted and a locked position to hold the bolt. The upper end of the bolt includes a knob for fine adjustment of the router. U.S. Pat. No. 4,938,264 to Ferenczffy discloses a clamping screw for use as a course adjustment mechanism. U.S. Pat. No. 5,191,921 to McCurry discloses a pinion and gear arrangement as a course adjustment mechanism. However, in each of these constructions, the fine adjustment mechanism has a limited travel length, and both the course and fine adjustment mechanisms may need to be reset and zeroed repetitively in order to arrive at the final cutting depth or height.
In prior art constructions, it can be difficult to adjust the cutting height of the plunge base router when the router is in an inverted position due to the weight of the router. The operator often finds it awkward to reach under a router table to press up on the router when adjusting the cutting height. It is therefore believed to be desirable to have a plunge base router that assists the operator with supporting the weight of the router during adjustment of the router in the inverted position.
After a final cutting height or depth is established, most plunge base routers include a post lock lever for locking the router in a selected position. The post lock lever is normally biased to the locked position, and the user must press on the post lock lever to release a locking mechanism so that the housing can be moved relative to the base. However, pressing the post lock lever when the router is in the inverted position and mounted under a router table can be awkward and difficult. It is therefore believed to be desirable to incorporate a mechanism for holding the post lock lever in the released position for easier adjustment of the router.
Plunge base routers typically have a compression spring that biases the housing away from the base and this compression spring can make it more difficult to mount the plunge base router in the inverted position under a router table. In particular, when an operator is mounting the router in the inverted position under a router table, the operator must hold the substantial weight of the router as well as push against the force of the compression spring in order to mount the router in the inverted position. Effectively, the compression spring adds to the weight of the router when an operator mounts it for inverted use. It is therefore believed to be desirable to provide a mechanism for defeating the force of the compression spring when the router is to be used in the inverted position.
The plunge base router of the present invention is particularly suited for use in either an upright position or an inverted position under a router table. The router includes several advantageous features to facilitate such use, and includes an advantageous mechanism for adjusting the cutting depth or height of the router. The router includes a base, a motor to rotate a bit, and a housing encasing the motor and being movable relative to the base on at least one guide post for adjustment of a cutting depth or height of the bit. The router further includes a return spring for providing a spring force between the base and the housing and biasing the housing away from the base.
In an embodiment, the router includes a means for defeating the spring force of the return spring on the router. The return spring defeat means is particularly advantageous for using the router in an inverted position because the operator does not need to struggle against both the weight of the router and the force of the return spring when mounting the router under a router table.
In an embodiment, the return spring defeat means includes a spring rod mounted within the return spring and having a first end engaging the return spring and second end having a groove and a head. A spring clip is movably mounted in the base and is movable between a first position not engaged with the spring rod and a second position engaged in the groove in the spring rod to vertically lock the spring rod and to defeat the return spring. When the spring rod is vertically locked, the first end of the spring rod that engages the return spring holds the return spring in a compressed condition or state so that its spring force is defeated. The base further includes a button that engages the spring clip and is adapted to selectively move the spring clip between the first position in which it does not engage the spring rod and the second position in which it engages the spring rod and defeats the return spring.
In an embodiment, the first or top end of the spring rod includes a snap ring that engages the top of the return spring, and when the spring clip locks the spring rod, the snap ring holds the return spring in the compressed state or condition.
In an embodiment, the spring clip includes first, second and third legs that form a triangle. The first leg extends under the button and biases the button toward the upward position. The second leg includes a free end that rides along the side of the button. The button includes a top portion that can be depressed by the operator, a small diameter mid-portion, and a large diameter bottom portion. In use, the button is depressed so that the free end of the spring clip moves into the smaller diameter mid-portion and the free end also engages the groove in the spring rod to vertically lock it in position. The button can then be depressed again so that the free end of the spring clip is moved adjacent to the larger diameter portion and the spring clip is moved away from the spring rod so that it does not lock it in position.
In an embodiment, the plunge base router of the present invention includes both a course adjustment and a fine adjustment mechanism. The adjustment mechanisms include a rod vertically mounted on the housing and being axially movable relative to the housing to set a cutting depth of the router. The rod preferably takes the form of a worm rod having a threaded portion. A course adjustment knob is connected to a gear mounted within the housing and the gear engages the threaded portion of the worm rod. The course adjustment knob and gear are rotatable to cause axial movement of the rod relative to the housing. A gear lock lever is also provided for locking the course adjustment knob and gear in a selected position. When the course adjustment knob and gear are locked in a selected position, the gear acts as a nut against which the worm rod can travel.
The depth adjustment mechanism further includes a fine adjustment knob secured to the rod for rotating the rod around its longitudinal axis. The fine adjustment knob and rod are rotatable, when the gear lever locks the gear in the selected position, to cause axial movement of the rod relative to the housing.
In use, the course and fine adjustment mechanism are used to adjust the position of the rod relative to the housing so that a free end of the rod is positioned a selected distance away from a surface on the base of the router. When the router is plunged, the free end of the rod hits the surface on the base and sets the cutting height or depth of the router.
In an embodiment, the router includes a rotatable depth stop mounted on the base under the worm rod. The rotatable depth lock includes a surface for engaging the rod and fixing the relative position of the housing with respect to the base to set the cutting depth or height of the router.
In an embodiment, the rotatable depth lock also includes a protrusion adapted for engaging a groove on the free end of the rod and locking the rod to the base. The depth lock is rotatable between a first position in which the protrusion engages the groove on the free end of the rod and locks the rod to the base, and a second position in which the protrusion does not engage the groove in order to allow axial movement of the rod. The rotatable depth lock is advantageously used to lock the rod to the base when it is desired to use the plunge base router in an inverted position. In the inverted position, the rod that is fixed to both the housing and the base help support the weight of the housing and motor, which makes it easier for the operator to adjust the cutting height or depth of the router.
In an embodiment, the depth stop includes a keyhole having a first opening large enough to receive the head and groove of the worm rod, and a second opening smaller than the head of the worm rod and being defined by the protrusion that engages the groove of the rod to lock the rod to the base. In use, the head of the rod are inserted into the first opening, and then the rotatable depth stop is rotated so that the protrusion of the second opening engages the groove and locks the rod to the base.
The rotatable depth stop may also include a recess on its underside for trapping the head on the rod. This prevents the rod from becoming dislodged for the rotatable depth stop during use of the router.
In an embodiment, the plunge base router includes a post lock lever and a means for holding the post lock lever in the released position. The post lock lever includes a lock element movable between a locked position wherein the housing is fixed relative to the base and a released position wherein the housing is movable relative to the base. A torsion spring biases the post lock lever and lock element into the lock position. A latch is provided that is movable to secure the post lock lever and lock element in the released position when desired. The latch is particularly useful for holding the post lock lever in the released position when it is desired to mount the router in an inverted position under a router table.
In an embodiment, the latch is mounted on the post lock lever, and a pin pivotally secures the latch to the lever. The latch includes a distal end that can project outwardly from the lever to engage a boss on the housing and hold the post lock lever in the released position. A second spring may be provided for biasing one end of the latch outward, and that end of the latch can then be depressed so that the latch pivots and the distal end engages the boss on the housing. The latch is particularly advantageous for defeating the post lock lever and holding it in the released position when it is desired to use the plunge base router in the inverted position under a router table.
These and numerous other features and advantages of the present invention will become readily apparent from the following description, the accompanying drawings and the appended claims.